Is it possible to over-charge a lithium mobile battery?

Not really - provided you use the correct charger, and the battery doesn't heat up to above 40 degrees Cels. However, an incorrect charger that pumps excessive voltage into the battery can lead to overheating. Bad, disastrous overheating. Check the BatteryUniversity on the subject and for more battery tips check out Lewis' article here on mobot

Not really - provided you use the correct charger, and the battery doesn't heat up to above 40 degrees Cels. However, an incorrect charger that pumps excessive voltage into the battery can lead to overheating. Bad, disastrous overheating. Check the BatteryUniversity on the subject and for more battery tips check out Lewis' article here on mobot

I find some chargers warm up more than others.
I don't know what phone you use, but for some OS's there are apps/widgets that display the battery temperature. Don't ask me how accurate they are though.